21903964993 has 4 divisors (see below), whose sum is σ = 23192433540. Its totient is φ = 20615496448.

The previous prime is 21903964991. The next prime is 21903965003. The reversal of 21903964993 is 39946930912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13621690944 + 8282274049 = 116712^2 + 91007^2 .

It is a cyclic number.

It is not a de Polignac number, because 21903964993 - 2¹ = 21903964991 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21903964991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 644234248 + ... + 644234281.

It is an arithmetic number, because the mean of its divisors is an integer number (5798108385).

Almost surely, 2^21903964993 is an apocalyptic number.

It is an amenable number.

21903964993 is a deficient number, since it is larger than the sum of its proper divisors (1288468547).

21903964993 is a wasteful number, since it uses less digits than its factorization.

21903964993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288468546.

The product of its (nonzero) digits is 2834352, while the sum is 55.

The spelling of 21903964993 in words is "twenty-one billion, nine hundred three million, nine hundred sixty-four thousand, nine hundred ninety-three".